The Experts below are selected from a list of 6248403 Experts worldwide ranked by ideXlab platform
Christopher L. Brace - One of the best experts on this subject based on the ideXlab platform.
-
Analysis of iodinated contrast delivered during thermal Ablation: is material trapped in the Ablation zone?
Physics in medicine and biology, 2016Co-Authors: Christopher L. BraceAbstract:Intra-procedural contrast-enhanced CT (CECT) has been proposed to evaluate treatment efficacy of thermal Ablation. We hypothesized that contrast material delivered concurrently with thermal Ablation may become trapped in the Ablation zone, and set out to determine whether such an effect would impact Ablation visualization. CECT images were acquired during microwave Ablation in normal porcine liver with: (A) normal blood perfusion and no iodinated contrast, (B) normal perfusion and iodinated contrast infusion or (C) no blood perfusion and residual iodinated contrast. Changes in CT attenuation were analyzed from before, during and after Ablation to evaluate whether contrast was trapped inside of the Ablation zone. Visualization was compared between groups using post-Ablation contrast-to-noise ratio (CNR). Attenuation gradients were calculated at the Ablation boundary and background to quantitate Ablation conspicuity. In Group A, attenuation decreased during Ablation due to thermal expansion of tissue water and water vaporization. The Ablation zone was difficult to visualize (CNR = 1.57 ± 0.73, boundary gradient = 0.7 ± 0.4 HU mm(-1)), leading to Ablation diameter underestimation compared to gross pathology. Group B Ablations saw attenuation increase, suggesting that iodine was trapped inside the Ablation zone. However, because the normally perfused liver increased even more, Group B Ablations were more visible than Group A (CNR = 2.04 ± 0.84, boundary gradient = 6.3 ± 1.1 HU mm(-1)) and allowed accurate estimation of the Ablation zone dimensions compared to gross pathology. Substantial water vaporization led to substantial attenuation changes in Group C, though the Ablation zone boundary was not highly visible (boundary gradient = 3.9 ± 1.1 HU mm(-1)). Our results demonstrate that despite iodinated contrast being trapped in the Ablation zone, Ablation visibility was highest when contrast is delivered intra-procedurally. Therefore, CECT may be feasible for real-time thermal Ablation monitoring.
-
Evaluation of a Thermoprotective Gel for Hydrodissection During Percutaneous Microwave Ablation: In Vivo Results
CardioVascular and Interventional Radiology, 2015Co-Authors: Anna J. Moreland, Fred T. Lee, Meghan G. Lubner, Timothy J. Ziemlewicz, Douglas R. Kitchin, J. Louis Hinshaw, Alexander D. Johnson, Christopher L. BraceAbstract:Purpose To evaluate whether thermoreversible poloxamer 407 15.4 % in water (P407) can protect non-target tissues adjacent to microwave (MW) Ablation zones in a porcine model. Materials and Methods MW Ablation antennas were placed percutaneously into peripheral liver, spleen, or kidney (target tissues) under US and CT guidance in five swine such that the expected Ablation zones would extend into adjacent diaphragm, body wall, or bowel (non-target tissues). For experimental Ablations, P407 (a hydrogel that transitions from liquid at room temperature to semi-solid at body temperature) was injected into the potential space between target and non-target tissues, and the presence of a gel barrier was verified on CT. No barrier was used for controls. MW Ablation was performed at 65 W for 5 min. Thermal damage to target and non-target tissues was evaluated at dissection. Results Antennas were placed 7 ± 3 mm from the organ surface for both control and gel-protected Ablations ( p = 0.95). The volume of gel deployed was 49 ± 27 mL, resulting in a barrier thickness of 0.8 ± 0.5 cm. Ablations extended into non-target tissues in 12/14 control Ablations (mean surface area = 3.8 cm^2) but only 4/14 gel-protected Ablations (mean surface area = 0.2 cm^2; p = 0.0005). The gel barrier remained stable at the injection site throughout power delivery. Conclusion When used as a hydrodissection material, P407 protected non-targeted tissues and was successfully maintained at the injection site for the duration of power application. Continued investigations to aid clinical translation appear warranted.
-
Computational modelling of microwave tumour Ablations.
International Journal of Hyperthermia, 2013Co-Authors: Jason Chiang, Peng Wang, Christopher L. BraceAbstract:Microwave tissue heating is being increasingly utilised in several medical applications, including focal tumour Ablation, cardiac Ablation, haemostasis and resection assistance. Computational modelling of microwave Ablations is a precise and repeatable technique that can assist with microwave system design, treatment planning and procedural analysis. Advances in coupling temperature and water content to electrical and thermal properties, along with tissue contraction, have led to increasingly accurate computational models. Developments in experimental validation have led to broader acceptability and applicability of these newer models. This review will discuss the basic theory, current trends and future direction of computational modelling of microwave Ablations.
-
Visualizing ex vivo radiofrequency and microwave Ablation zones using electrode vibration elastography
Medical physics, 2012Co-Authors: Ryan J. Dewall, Tomy Varghese, Christopher L. BraceAbstract:Purpose: Electrode vibration elastography is a new shear waveimaging technique that can be used to visualize thermal Ablation zones. Prior work has shown the ability of electrode vibration elastography to delineate radiofrequency Ablations; however, there has been no previous study of delineation of microwave Ablations or radiological–pathological correlations using multiple observers. Methods: Radiofrequency and microwave Ablations were formed inex vivo bovine livertissue. Their visualization was compared on shear wave velocity and maximum displacement images.Ablation dimensions were compared to gross pathology. Elastographic imaging and gross pathology overlap and interobserver variability were quantified using similarity measures. Results: Elastographic imaging correlated with gross pathology. Correlation of area estimates was better in radiofrequency than in microwave Ablations, with Pearson coefficients of 0.79 and 0.54 on shear wave velocity images and 0.90 and 0.70 on maximum displacement images for radiofrequency and microwave Ablations, respectively. The absolute relative difference in area between elastographic imaging and gross pathology was 18.9% and 22.9% on shear wave velocity images and 16.0% and 23.1% on maximum displacement images for radiofrequency and microwave Ablations, respectively. Conclusions: Statistically significant radiological–pathological correlation was observed in this study, but correlation coefficients were lower than other modulus imaging techniques, most notably in microwave Ablations. Observers provided similar delineations for most thermal Ablations. These results suggest that electrode vibration elastography is capable of imaging thermal Ablations, but refinement of the technique may be necessary before it can be used to monitor thermal Ablation procedures clinically.
-
Multiple-Antenna Microwave Ablation: Spatially Distributing Power Improves Thermal Profiles and Reduces Invasiveness.
Journal of interventional oncology, 2009Co-Authors: Paul F. Laeseke, Fred T. Lee, Van Der Weide Dw, Christopher L. BraceAbstract:BACKGROUND: Microwave Ablation is an emerging tumor Ablation modality. To date, microwave systems have generally utilized single large-diameter antennas to deliver high input powers. OBJECTIVE: To determine whether spatially distributing power through an array of multiple smaller antennas creates a more uniform thermal profile and increases peripheral tissue temperatures when compared with microwave Ablation using a single larger antenna. METHODS: Microwave Ablations were performed in ex vivo bovine liver using a single 2.45-GHz magnetron generator and a constant total input power (90 W) delivered through either a single 13-gauge antenna, two 17-gauge antennas, or three 18-gauge antennas. Multiple antennas were driven coherently. Temperatures were recorded at 5-mm radial distances and the resulting thermal profiles and Ablation zones were compared using analysis of variance. RESULTS: Multiple-antenna configurations were less invasive (ie, the area of tissue punctured was smaller) than the single-antenna configuration; despite this, Ablation zones created using multiple smaller antennas were larger and as circular when compared with those created using a single larger antenna. Multiple-antenna configurations resulted in more uniform thermal profiles and higher peripheral tissue temperatures. CONCLUSION: Distributing power evenly among multiple smaller antennas resulted in larger Ablation zones with more uniform thermal profiles than more invasive Ablations with a larger single antenna.
David L Ross - One of the best experts on this subject based on the ideXlab platform.
-
high spatial resolution thermal mapping of radiofrequency Ablation lesions using a novel thermochromic liquid crystal myocardial phantom
Journal of Cardiovascular Electrophysiology, 2013Co-Authors: Sujitha Thavapalachandran, Christine Midekin, W Chik, Gopal Sivagangabalan, Jim Pouliopoulos, M A Barry, David L Ross, Stuart P ThomasAbstract:BACKGROUND: Radiofrequency (RF) Ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF Ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro Ablation lesions. METHODS AND RESULTS: The myocardial phantom was constructed from a vertical sheet of TLC film, with color change between 50 °C (red) to 78 °C (black), embedded within a gel matrix, with impedance titrated to equal that of myocardium. Saline, with impedance titrated to blood values at 37 °C, was used as supernatant. A total of 51 RF Ablations were performed. This comprised 17 Ablations in the thermochromic gel phantom, bovine myocardial in vitro targets and ovine in vivo Ablations, respectively. There was no difference in lesion dimensions between the thermochromic gel and in vivo Ablations (lesion width 10.2 ± 0.2 vs 10.2 ± 2.4, P = 0.93; and depth 6.3 ± 0.1 vs 6.5 ± 1.7, P = 0.74). The spatial resolution of the thermochromic film was tested using 2 thermal point-sources that were progressively opposed and was demonstrated to be <300 μm. CONCLUSIONS: High spatial resolution thermal mapping of in vitro RF lesions with spatial resolution of at least 300 μm is possible using a thermochromic liquid crystal myocardial phantom model, with a good correlation to in vivo RF Ablations. This model may be useful for assessing the thermal characteristics of RF lesions created using different Ablation parameters and catheter technologies.
-
High Spatial Resolution Thermal Mapping of Radiofrequency Ablation Lesions Using a Novel Thermochromic Liquid Crystal Myocardial Phantom
Journal of Cardiovascular Electrophysiology, 2013Co-Authors: W Chik, Sujitha Thavapalachandran, Christine Midekin, Gopal Sivagangabalan, Jim Pouliopoulos, M A Barry, David L Ross, Stuart P Thomas, Alistair McewanAbstract:BACKGROUND: Radiofrequency (RF) Ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF Ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro Ablation lesions. METHODS AND RESULTS: The myocardial phantom was constructed from a vertical sheet of TLC film, with color change between 50 °C (red) to 78 °C (black), embedded within a gel matrix, with impedance titrated to equal that of myocardium. Saline, with impedance titrated to blood values at 37 °C, was used as supernatant. A total of 51 RF Ablations were performed. This comprised 17 Ablations in the thermochromic gel phantom, bovine myocardial in vitro targets and ovine in vivo Ablations, respectively. There was no difference in lesion dimensions between the thermochromic gel and in vivo Ablations (lesion width 10.2 ± 0.2 vs 10.2 ± 2.4, P = 0.93; and depth 6.3 ± 0.1 vs 6.5 ± 1.7, P = 0.74). The spatial resolution of the thermochromic film was tested using 2 thermal point-sources that were progressively opposed and was demonstrated to be
-
High Spatial Resolution Thermal Mapping of Radiofrequency Ablation Lesions Using a Novel Thermochromic Liquid Crystal Myocardial Phantom
Journal of cardiovascular electrophysiology, 2013Co-Authors: W Chik, Sujitha Thavapalachandran, Christine Midekin, Gopal Sivagangabalan, Jim Pouliopoulos, M A Barry, David L Ross, Stuart P Thomas, Toon Wei Lim, Alistair McewanAbstract:High-Resolution Thermal Mapping of RF Ablation LesionsBackground Radiofrequency (RF) Ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF Ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro Ablation lesions. Methods and Results The myocardial phantom was constructed from a vertical sheet of TLC film, with color change between 50 °C (red) to 78 °C (black), embedded within a gel matrix, with impedance titrated to equal that of myocardium. Saline, with impedance titrated to blood values at 37 °C, was used as supernatant. A total of 51 RF Ablations were performed. This comprised 17 Ablations in the thermochromic gel phantom, bovine myocardial in vitro targets and ovine in vivo Ablations, respectively. There was no difference in lesion dimensions between the thermochromic gel and in vivo Ablations (lesion width 10.2 ± 0.2 vs 10.2 ± 2.4, P = 0.93; and depth 6.3 ± 0.1 vs 6.5 ± 1.7, P = 0.74). The spatial resolution of the thermochromic film was tested using 2 thermal point-sources that were progressively opposed and was demonstrated to be
-
Cooled Intramural Needle Catheter Ablation Creates Deeper Lesions than Irrigated Tip Catheter Ablation
Pacing and clinical electrophysiology : PACE, 2004Co-Authors: Aravinda Thiagalingam, David L Ross, Craig R. Campbell, Anita Boyd, Vicki Eipper, Pramesh KovoorAbstract:Endocardial radiofrequency Ablation of the left ventricle does not create transmural lesions reliably even with active electrode cooling. The authors developed a prototype catheter with an internally cooled needle electrode that could be advanced an adjustable distance into the myocardium. Freshly excised hearts from eight male sheep were perfused and superfused using oxygenated ovine blood. Ablations were performed for 2 minutes using the prototype catheter and a conventional endocardial 5-mm irrigated tip Ablation catheter at target temperatures of 80 degrees C and 50 degrees C, respectively. The prototype catheter needle was inserted 12 mm deep for all Ablations. The maximal power and irrigation rate was 50 W, 20 mL/min for the irrigated tip catheter and 20 W, 10 mL/min for the intramural needle catheter. Intramural needle lesions were significantly deeper (13.5 +/- 2.3 vs 9.1 +/- 1.3 mm, P < 0.01) but less wide (8.7 +/- 1.5 vs 12.7 +/- 1.9 mm, P < 0.01) than irrigated tip lesions. Popping occurred during 12 (37%) of the 32 irrigated tip Ablations. Popping did not occur during intramural needle Ablation. The cooled intramural needle Ablation catheter creates lesions that are significantly deeper than irrigated tip catheters with less tissue boiling. In contrast to irrigated tip Ablation, electrode temperature monitoring can be used to determine if a lesion has been created during intramural needle Ablation. The cooled intramural needle Ablation lesions were of a clinically useful width, addressing one of the main recognized deficiencies of intramural needle Ablation.
W Chik - One of the best experts on this subject based on the ideXlab platform.
-
high spatial resolution thermal mapping of radiofrequency Ablation lesions using a novel thermochromic liquid crystal myocardial phantom
Journal of Cardiovascular Electrophysiology, 2013Co-Authors: Sujitha Thavapalachandran, Christine Midekin, W Chik, Gopal Sivagangabalan, Jim Pouliopoulos, M A Barry, David L Ross, Stuart P ThomasAbstract:BACKGROUND: Radiofrequency (RF) Ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF Ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro Ablation lesions. METHODS AND RESULTS: The myocardial phantom was constructed from a vertical sheet of TLC film, with color change between 50 °C (red) to 78 °C (black), embedded within a gel matrix, with impedance titrated to equal that of myocardium. Saline, with impedance titrated to blood values at 37 °C, was used as supernatant. A total of 51 RF Ablations were performed. This comprised 17 Ablations in the thermochromic gel phantom, bovine myocardial in vitro targets and ovine in vivo Ablations, respectively. There was no difference in lesion dimensions between the thermochromic gel and in vivo Ablations (lesion width 10.2 ± 0.2 vs 10.2 ± 2.4, P = 0.93; and depth 6.3 ± 0.1 vs 6.5 ± 1.7, P = 0.74). The spatial resolution of the thermochromic film was tested using 2 thermal point-sources that were progressively opposed and was demonstrated to be <300 μm. CONCLUSIONS: High spatial resolution thermal mapping of in vitro RF lesions with spatial resolution of at least 300 μm is possible using a thermochromic liquid crystal myocardial phantom model, with a good correlation to in vivo RF Ablations. This model may be useful for assessing the thermal characteristics of RF lesions created using different Ablation parameters and catheter technologies.
-
High Spatial Resolution Thermal Mapping of Radiofrequency Ablation Lesions Using a Novel Thermochromic Liquid Crystal Myocardial Phantom
Journal of Cardiovascular Electrophysiology, 2013Co-Authors: W Chik, Sujitha Thavapalachandran, Christine Midekin, Gopal Sivagangabalan, Jim Pouliopoulos, M A Barry, David L Ross, Stuart P Thomas, Alistair McewanAbstract:BACKGROUND: Radiofrequency (RF) Ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF Ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro Ablation lesions. METHODS AND RESULTS: The myocardial phantom was constructed from a vertical sheet of TLC film, with color change between 50 °C (red) to 78 °C (black), embedded within a gel matrix, with impedance titrated to equal that of myocardium. Saline, with impedance titrated to blood values at 37 °C, was used as supernatant. A total of 51 RF Ablations were performed. This comprised 17 Ablations in the thermochromic gel phantom, bovine myocardial in vitro targets and ovine in vivo Ablations, respectively. There was no difference in lesion dimensions between the thermochromic gel and in vivo Ablations (lesion width 10.2 ± 0.2 vs 10.2 ± 2.4, P = 0.93; and depth 6.3 ± 0.1 vs 6.5 ± 1.7, P = 0.74). The spatial resolution of the thermochromic film was tested using 2 thermal point-sources that were progressively opposed and was demonstrated to be
-
High Spatial Resolution Thermal Mapping of Radiofrequency Ablation Lesions Using a Novel Thermochromic Liquid Crystal Myocardial Phantom
Journal of cardiovascular electrophysiology, 2013Co-Authors: W Chik, Sujitha Thavapalachandran, Christine Midekin, Gopal Sivagangabalan, Jim Pouliopoulos, M A Barry, David L Ross, Stuart P Thomas, Toon Wei Lim, Alistair McewanAbstract:High-Resolution Thermal Mapping of RF Ablation LesionsBackground Radiofrequency (RF) Ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF Ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro Ablation lesions. Methods and Results The myocardial phantom was constructed from a vertical sheet of TLC film, with color change between 50 °C (red) to 78 °C (black), embedded within a gel matrix, with impedance titrated to equal that of myocardium. Saline, with impedance titrated to blood values at 37 °C, was used as supernatant. A total of 51 RF Ablations were performed. This comprised 17 Ablations in the thermochromic gel phantom, bovine myocardial in vitro targets and ovine in vivo Ablations, respectively. There was no difference in lesion dimensions between the thermochromic gel and in vivo Ablations (lesion width 10.2 ± 0.2 vs 10.2 ± 2.4, P = 0.93; and depth 6.3 ± 0.1 vs 6.5 ± 1.7, P = 0.74). The spatial resolution of the thermochromic film was tested using 2 thermal point-sources that were progressively opposed and was demonstrated to be
Alistair Mcewan - One of the best experts on this subject based on the ideXlab platform.
-
High Spatial Resolution Thermal Mapping of Radiofrequency Ablation Lesions Using a Novel Thermochromic Liquid Crystal Myocardial Phantom
Journal of Cardiovascular Electrophysiology, 2013Co-Authors: W Chik, Sujitha Thavapalachandran, Christine Midekin, Gopal Sivagangabalan, Jim Pouliopoulos, M A Barry, David L Ross, Stuart P Thomas, Alistair McewanAbstract:BACKGROUND: Radiofrequency (RF) Ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF Ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro Ablation lesions. METHODS AND RESULTS: The myocardial phantom was constructed from a vertical sheet of TLC film, with color change between 50 °C (red) to 78 °C (black), embedded within a gel matrix, with impedance titrated to equal that of myocardium. Saline, with impedance titrated to blood values at 37 °C, was used as supernatant. A total of 51 RF Ablations were performed. This comprised 17 Ablations in the thermochromic gel phantom, bovine myocardial in vitro targets and ovine in vivo Ablations, respectively. There was no difference in lesion dimensions between the thermochromic gel and in vivo Ablations (lesion width 10.2 ± 0.2 vs 10.2 ± 2.4, P = 0.93; and depth 6.3 ± 0.1 vs 6.5 ± 1.7, P = 0.74). The spatial resolution of the thermochromic film was tested using 2 thermal point-sources that were progressively opposed and was demonstrated to be
-
High Spatial Resolution Thermal Mapping of Radiofrequency Ablation Lesions Using a Novel Thermochromic Liquid Crystal Myocardial Phantom
Journal of cardiovascular electrophysiology, 2013Co-Authors: W Chik, Sujitha Thavapalachandran, Christine Midekin, Gopal Sivagangabalan, Jim Pouliopoulos, M A Barry, David L Ross, Stuart P Thomas, Toon Wei Lim, Alistair McewanAbstract:High-Resolution Thermal Mapping of RF Ablation LesionsBackground Radiofrequency (RF) Ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF Ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro Ablation lesions. Methods and Results The myocardial phantom was constructed from a vertical sheet of TLC film, with color change between 50 °C (red) to 78 °C (black), embedded within a gel matrix, with impedance titrated to equal that of myocardium. Saline, with impedance titrated to blood values at 37 °C, was used as supernatant. A total of 51 RF Ablations were performed. This comprised 17 Ablations in the thermochromic gel phantom, bovine myocardial in vitro targets and ovine in vivo Ablations, respectively. There was no difference in lesion dimensions between the thermochromic gel and in vivo Ablations (lesion width 10.2 ± 0.2 vs 10.2 ± 2.4, P = 0.93; and depth 6.3 ± 0.1 vs 6.5 ± 1.7, P = 0.74). The spatial resolution of the thermochromic film was tested using 2 thermal point-sources that were progressively opposed and was demonstrated to be
Jim Pouliopoulos - One of the best experts on this subject based on the ideXlab platform.
-
renal artery branch denervation evaluation of lesion characteristics using a thermochromic liquid crystal phantom model
Heart Lung and Circulation, 2020Co-Authors: Sara I. Al Raisi, M. Barry, John Swinnen, Pierre Qian, Jim Pouliopoulos, Aravinda Thiagalingam, Pramesh KovoorAbstract:Background Lately, combined main vessel and branch Ablation has been recommended during radiofrequency (RF) renal artery denervation. Utilising a validated renal artery phantom model, we aimed (1) to determine thermal injury extent (lesion depth, width and circumferential coverage) and electrode-tissue interface temperature for branch renal artery Ablation, and (2) to compare the extent of thermal injury for branch versus main vessel Ablation using the same RF System. Methods We employed a gel based renal artery phantom model simulating variable vessel diameter and flow, which incorporated a temperature sensitive thermochromic-liquid-crystal (TLC) film for assessing RF Ablation thermodynamics. Ablations in a branch renal artery model (n = 32) were performed using Symplicity Spyral (Medtronic, Minneapolis, MN, USA). Lesion dimensions defined by the 51 °C isotherm, circumferential injury coverage, and electrode-tissue interface temperature were measured for all Ablations at 60 seconds. Results Lesion dimensions were 2.13 ± 0.13 mm and 4.13 ± 0.18 mm for depth and width, respectively, involving 23% of the vessel circumference. Maximum electrode-tissue interface temperature was 68.31 ± 2.29 °C. No significant difference in lesion depth between branch and main vessel Ablations was found (Δ = 0.02 mm, p = 0.60). However, lesions were wider in the branch (Δ=0.49 mm, p Conclusions In the phantom model, branch Ablations were of similar depth but had larger width and circumferential coverage compared to main vessel Ablations. Concerning safety, no overheating at the electrode-tissue interface was observed.
-
high spatial resolution thermal mapping of radiofrequency Ablation lesions using a novel thermochromic liquid crystal myocardial phantom
Journal of Cardiovascular Electrophysiology, 2013Co-Authors: Sujitha Thavapalachandran, Christine Midekin, W Chik, Gopal Sivagangabalan, Jim Pouliopoulos, M A Barry, David L Ross, Stuart P ThomasAbstract:BACKGROUND: Radiofrequency (RF) Ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF Ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro Ablation lesions. METHODS AND RESULTS: The myocardial phantom was constructed from a vertical sheet of TLC film, with color change between 50 °C (red) to 78 °C (black), embedded within a gel matrix, with impedance titrated to equal that of myocardium. Saline, with impedance titrated to blood values at 37 °C, was used as supernatant. A total of 51 RF Ablations were performed. This comprised 17 Ablations in the thermochromic gel phantom, bovine myocardial in vitro targets and ovine in vivo Ablations, respectively. There was no difference in lesion dimensions between the thermochromic gel and in vivo Ablations (lesion width 10.2 ± 0.2 vs 10.2 ± 2.4, P = 0.93; and depth 6.3 ± 0.1 vs 6.5 ± 1.7, P = 0.74). The spatial resolution of the thermochromic film was tested using 2 thermal point-sources that were progressively opposed and was demonstrated to be <300 μm. CONCLUSIONS: High spatial resolution thermal mapping of in vitro RF lesions with spatial resolution of at least 300 μm is possible using a thermochromic liquid crystal myocardial phantom model, with a good correlation to in vivo RF Ablations. This model may be useful for assessing the thermal characteristics of RF lesions created using different Ablation parameters and catheter technologies.
-
High Spatial Resolution Thermal Mapping of Radiofrequency Ablation Lesions Using a Novel Thermochromic Liquid Crystal Myocardial Phantom
Journal of Cardiovascular Electrophysiology, 2013Co-Authors: W Chik, Sujitha Thavapalachandran, Christine Midekin, Gopal Sivagangabalan, Jim Pouliopoulos, M A Barry, David L Ross, Stuart P Thomas, Alistair McewanAbstract:BACKGROUND: Radiofrequency (RF) Ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF Ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro Ablation lesions. METHODS AND RESULTS: The myocardial phantom was constructed from a vertical sheet of TLC film, with color change between 50 °C (red) to 78 °C (black), embedded within a gel matrix, with impedance titrated to equal that of myocardium. Saline, with impedance titrated to blood values at 37 °C, was used as supernatant. A total of 51 RF Ablations were performed. This comprised 17 Ablations in the thermochromic gel phantom, bovine myocardial in vitro targets and ovine in vivo Ablations, respectively. There was no difference in lesion dimensions between the thermochromic gel and in vivo Ablations (lesion width 10.2 ± 0.2 vs 10.2 ± 2.4, P = 0.93; and depth 6.3 ± 0.1 vs 6.5 ± 1.7, P = 0.74). The spatial resolution of the thermochromic film was tested using 2 thermal point-sources that were progressively opposed and was demonstrated to be
-
High Spatial Resolution Thermal Mapping of Radiofrequency Ablation Lesions Using a Novel Thermochromic Liquid Crystal Myocardial Phantom
Journal of cardiovascular electrophysiology, 2013Co-Authors: W Chik, Sujitha Thavapalachandran, Christine Midekin, Gopal Sivagangabalan, Jim Pouliopoulos, M A Barry, David L Ross, Stuart P Thomas, Toon Wei Lim, Alistair McewanAbstract:High-Resolution Thermal Mapping of RF Ablation LesionsBackground Radiofrequency (RF) Ablation causes thermal mediated irreversible myocardial necrosis. This study aimed to (i) characterize the thermal characteristics of RF Ablation lesions with high spatial resolution using a thermochromic liquid crystal (TLC) myocardial phantom; and (ii) compare the thermochromic lesions with in vivo and in vitro Ablation lesions. Methods and Results The myocardial phantom was constructed from a vertical sheet of TLC film, with color change between 50 °C (red) to 78 °C (black), embedded within a gel matrix, with impedance titrated to equal that of myocardium. Saline, with impedance titrated to blood values at 37 °C, was used as supernatant. A total of 51 RF Ablations were performed. This comprised 17 Ablations in the thermochromic gel phantom, bovine myocardial in vitro targets and ovine in vivo Ablations, respectively. There was no difference in lesion dimensions between the thermochromic gel and in vivo Ablations (lesion width 10.2 ± 0.2 vs 10.2 ± 2.4, P = 0.93; and depth 6.3 ± 0.1 vs 6.5 ± 1.7, P = 0.74). The spatial resolution of the thermochromic film was tested using 2 thermal point-sources that were progressively opposed and was demonstrated to be
